Prey handling and consumption by northern goshawks (Accipiter gentilis) : a feeding experiment

Abstract

Although the northern goshawk (Accipiter gentilis) is a well-studied raptor, little is known about its prey handling behaviour and food requirement in different temperatures. Such knowledge is important for understanding its prey selection. I collected data on four wild female goshawks by video monitoring their handling of presented prey, 9 mammalian prey and 31 avian prey. I also conducted eight feeding trials, where I presented a mammalian and avian prey simultaneously, to see what the goshawk preferred to feed on. In each of these feeding experiments the goshawk fed on avian prey. The goshawks were more likely to start feeding from the head on small avian prey, and from the breast of larger avian prey. The goshawks were more efficient when feeding on a small avian prey than a large avian prey, and more efficient at high temperature and when proportion of remains was high. The piece size decreased with increasing prey body mass, with lower temperatures, and with lower proportion of remains left. Both the feeding efficiency and piece mass decreased when the mammalian prey was frozen. The goshawks ingested more meat when temperatures were sub-zero. Based on this study, to have the highest handling efficiency, the goshawk should select a small prey, particularly on cold days when the prey would freeze fast.